Outgoing Limit not working

Hi,

i have defined 50 Emails per Hour Limit but one Email Adress can send over 130 Emails in 2 Seconds without Problems.
The Mail queu wont get filled or anything else.
It seems that the outgoing Limit for Mailboxes wont do his work.

OS Debian 8.10‬ Plesk Onyx
Version 17.5.3 Update #37

I double checked the Server wide Settings and the Settings within Subscription.
Makes no sense!!

View attachment 13922
This is the custom Settings for Customer and it stands on 50 Emails.
Customer could...

Outgoing Limit not working